Various mechanical structures are employed to fabricate a lock device, especially in the design of a complicated dual locking device for security to against terrorists. One conventional technique, relative to the dual locking device, is disclosed in U.S. Pat. No. 6,843,080. The dual locking device of U.S. Pat. No. 6,843,080 has a shifting member controlled by a combination lock to block or open a bendable shackle element from a corresponding locking hole. Under the control of the combination lock, the shifting member itself is both linear displaceable and deflectedable about a horizontal shaft. When a correct code of the combination lock is set, a stopper of the shackle element can be brought to push the shifting member so that the shifting member is forced to deflect and displace to come off the corresponding locking hole so as to release the shackle element from the locking hole.
One limitation of U.S. Pat. No. 6,843,080 for the dual locking device is the difficulty or impossibility of applying the shifting member with two motions on a zipper lock for securing a latch hole of a zipper.
Another conventional lock is disclosed in U.S. Pat. No. 6,912,880 and is also relative to the dual locking device, which has a stopping member to block or open a way of a push-button to constrain or release a lock tongue of the dual locking device. More specifically, the stopping member is pivotally mounted in a lock body under controls of a key lock and a combination lock. Moreover, the key lock is far from the stopping member and is linked via a linking member. Upon this complicated design, the conventional lock of the U.S. Pat. No. 6,912,880 is big in size for its complicated structure with extra elements, such as the linking member and two push-buttons.
For microminiaturization of the lock, it would be advantage to provide a dual locking device, which is capable of meeting the increasingly insistent requests for reduction in cost, weight, section, and dimensions with the same reliability and usability.
From the foregoing descriptions, it will be seen that room exists for improvements in the base.